Bimetal tank



A ril 13, 1943. A. J. KERCHER B IMETAL TANK Filed April 5. 1938 JT'IILII '7 v '1 'IE'I E INVENTQR. Ar/hur J. kercher 7:2

Patented "Apr. 13, 1943 UNITED STATES E PATENT OFFICE 2,310,437 1 Arthur 3: 2;, Application April 5, 1938, Serial N0.200,132

3Claims. ((1220-63) such devices'are subjected, is apt to cause detrimental corrosion.

In the past non-oorrodible tanks and containers have been made from relatively expensive metals and metal alloys, which, as distinguished from ordinary steel or base metal, are substantially non-corrodible for the service desired. For example copper, brass or bronzes have been used to a considerable extent, and more recently the so-called stainless alloys, such as Monel metal. All such metals or alloys are comparatively expensive, and in additiontheir use may involve manufacturing difficulties. It has been attempted to provide non-corrodible liners for base metal tanks, without notable success. For example electroplating and application of sprayed metal have been employed. Such coating methods are not reliable because it is difllcult to secure a protective layer of adequate thickness, uniformity and density, and because insufilclent latitude is available with respect to the composition of the liner desired. Furthermore technical difllculties are involved, which add to the cost of manuiacture. It has also been proposed to apply a sheet 'metal liner of non-corrodible metal, such as copper, to steel tanks. The methods and constructions used in the past however have failed, because the liners have been subject to stresses when in use, to cause failure and ultimate leakage.

It is an object of the present invention to provide a simple bi-metal tank or container, which will make use of available sheet metal stock of non-corrodible metals or metal alloys, for lining a base metal shell. It is another object of the invention to provide a novel method of manufacture, whereby such bi-metal tanks can be made in quantities with a high degree of uniiormity, and without thepossibility of undue stresses being applied to the liner when the tank is in use.

Further objects of the invention will appear from the following description in which the preferred embodiment of the invention has been set forth in detail in conjunction with the accompanying drawing.

- Referring to the drawing:

Fig. 1 is a side elevational view. showing a bimetal tank incorporating the presentv invention.

Fig. 2 is an enlarged cross-sectional detail, showingthe form or the liner when initially applied to the basemetal shell.

Fig. 3 is an enlarged cross-sectional detail,

showing one stage in the method of manuiacture,

in which corrugations in the end edges of th liner, are removed.

Fig. 4 is an enlaged cross-sectional detail, showing the manne in which a connectionor fitting can be applied to one side wall of the tank.

Fig. 5 is an enlarged cross-sectional detail, showing the manner in which the liner is pressed against the side walls of the tank, when internal pressure is applied. .j;

Fig. 6 is an enlarged cross-sectional detail, showing one stage in forming an end junction between the cylindrical side'jwalls of the shell, and one end wall. I t

Fig. 7 is a view similar 't o Fig. 6, but showing another stage in the man' facture, in which the end edge of the shell is t I (E orbent inwardly.

Fig. 8 is a view similar to g. 6, but illustrating a final stage in making the joint between the side and end walls. i

In carrying out the present 'vention I employ. a relatively inexpensive base tal, such as cold rolled steel, to form a strong oliter shell. As suming that a relatively simple tank is being formed, the outer shell consistsof cylindrically formed side walls I0, together with upper-and lower end walls II. The inner surfaces oi. the side walls ID are covered with a sheet metal liner I2, formed of relatively non-corrodible material such as copper or Monel metal. The end walls II are dished inwardly' as shown in Figs. 6 to 8' inclusive, and their inner'fa'ces are also covered by the liner portion l3.

In making the liner portion I2 for the cylindrical side walls, I prefer to proceed as follows: A sheet of the non-corrodible metal is first cut to proper size, and then bent to substantially cylindrical form, and the side edges suitably joined together to form a seam. This seam may employ two locking edges crimped together, as is well known by those skilled in the art, and suitable hard solder can be applied to insure against leakage.

The diameter to which the liner is initially formed is somewhat greater than the internal diameter of the cylindrical shell. For example for a shell having an internal diameter of about twelve inches, the circumference of the liner can be oversize to the extent of about ofan inch. The liner is then placed in a suitable corrugating machine, and a plurality of corrugations M provided which extend throughout the length tions of about inch in depth, with a spacing between valleys in the neighborhood of of an inch. It will be apparent however that such dimensions mayvary and are not critical. The corrugations should be such that the effective outside diameter of the liner is substantially reduced to a-value less than the internaldiameter of the shell. The liner, can now be introduced intothe cylindrical side walls of the shell, without difllculty.

The length ofthecylindrical portion of the liner is somewhat less than the length of the side walls iii. For. example with tanks of the order of 12 or 14 inches in diameter, the cylindrical liner portion l2 can be proportioned so that the side walls of the shell extend beyond the ends of the liner for a distance of say of an inch.

The next operation is to remove the corrugations from end margins l2a of the liner. This can be done by a simple rolling operation, which necessarily involves some compression of the liner, to eliminate all evidence of corrugations. It will be evident. that such a rolling operation causes the marginal portions l2a to snugly contact the adjacent surfaces of the shell. Assuming now that the corrugations have been removed from both end margins of the liner portion 12, the end walls 1 I can now be applied. The liner portion l3 for the end walls H can be shaped to snugly fit the end walls, by a suitable spinning operation. Note particularly that one margin edge l3a, extends over the flange I5.

The end walls H are so proportioned that when applied as shown in Fig. 6, there is a relatively snug fit so that the marginal edge portions l2a and l3a. are gripped between the flanges l5, and the side walls 10. Note that there are edges l2c l3c of the liner, which project outwardly beyond the flange l5. These edges can be bent inwardly as shown, to facilitate the soldering operation to follow.

The next step is to bend the projecting edges ii of the side walls 10, to afford annular recesses IT. This bending can be carried out by a rolling or peening operation, and should be such that the reduced internal diameter encompassed by the' edge I8, is substantially less than the diameter of the flanges IS.

The next operation is to braise or fuse the liner margins I21: and I30, together, and to also cause these margins to be bonded to the adjacent portions of the shell. In carrying out this fusing or .braising operation, it has been found convenient'to slowly rotate the tank, while a blow torch is applied to the bent portion is of the shell,to heat the same to an elevated temperature; After a suitable temperature has been reached hard solder or spelter is applied to the recess ll, together with suitable fiuxing material, whereby the spelter or hard solder penetrates to bond together the faces of liner margins Hu and [3a, and to bond together these margins to the adjacent surfaces of the base metal. Suificient excess spelter is applied to form a filler IQ for the recess l1, within which the edges I2c, I30 are embedded. It will be apparent from Fig. 8 that this filler of hard solder forms in effect an annular key between the end portions 16 and the end walls i I, whereby the end walls are firmly held in place against internal pressure, and whereby any internal pressure is eflectively transmitted from end walls II to the side walls 10. While fused spelter is being applied the projecting edges I2c, |3c facilifittings 2| or spuds can be provided in the end walls H, for making connection. with liquid pipes. Such fittings should be made of relatively non-corrodible metal or metal alloy, and in addition to being sealed with respect to the liner, they should be firmly bonded to the stronger metal of the shell. Such fittings, if required, are preferably applied to the end walls before these end walls are secured to the side walls, in th manner previously described. To apply a somewhat similar fitting 22 to the side walls, the corrugations must be removed from an annular portion l2b of the liner l2, thereby providing a substantially flat surface for bonding to the inner flange 23 of the spud, and to the adjacent base metal surfaces,

After forming the tank as described above, an internal hydraulic pressure is applied to test the same against leakage. The pressure applied is of such a value as to definitely reshape the corrugations in the liner portion 12. Thus as illustrated in Fig. 5, internal pressure has forced the liner portion 12 outwardly against the adjacent walls of the shell, wherebyportions l2c of the liner are definitely in contact with the adjacent walls of the. shell, while portions i2d remain as corrugations. With the corrugations i2d remaining throughout the life of the shell, it will be apparent that internal pressure applied to the tank, or circumferential expansion and contraction, can not subject the liner to disruptive stresses. In fact with internal pressure the liner is always subjected to circumferential compression, rather than tension. Thus adequate bearing is provided between the liner and the adjacent cylindrical walls of the shell, without imposing objectionable stresses upon the liner, and this is all accomplished without tediousfitting of the liner into the shell.

It will be evident that the bi-metal tank described above can be manufactured at reasonable cost. In most instances it can take the place of expensive tanks or containers, constructed entirely of non-corrodible metal. The manner in which the sealed joints are formed at the ends of the tank, does not involve the application of heat by fiame or are, directly to the metal liner. Thus there is no danger of striking or otherwise distorting or damaging the liner by excessive direct heating, and any stresses which may be temporarily developed during the fusion operation, are absorbed by the steel shell.

This application is a continuation in part of my co-pending application, Serial Number 73,269, filed Apr. 8, 1936.

I claim:

1. In a bi-metal tank, a base metal shell having end walls and cylindrical side walls, a noncorrodible sheet metal liner extending over the inner surfaces of the shell, the junction between each end and the side walls of the shell having marginal edge portions of the liner interposed between the same, and each end edge of the cylindrical side walls extending past the edge of the adjacent end wall being turned inwardly to overlap the adjacent end wall and forman annular recess, said annular recesses being filled with hard solder.

2. In a bi-metal tank, a metal shell formed of relatively corrodible sheet metal, said shell including substantially cylindrically-shaped side walls and end walls fitted within the side walls. the end walls being dished inwardly. a comparatively non-corrodible sheet metal liner extending over the inner surfaces of the shell, said liner including side portions extending over the side walls of the shell and end portions extending over the end Walls of the shell, said side and end portions of the liner having cylindrical shaped overlapping margins interposed between the side and end walls of the shell, said overlapping margins having their contacting faces bonded together to form a sealed joint and also having their inner and outer peripheral surfaces bonded to adjacent surfaces of the shell, the end edges of the shell extending beyond the adjacent edges of the end walls and being bent inwardly to form annular recesses adjacent the end edges of the liner, said recesses being filled with hard solder thereby locking the ends to the side walls of the shell.

3. In a bi-metaltank, a metal shell formed of relatively corrodible sheet metal, said shell including substantially cylindrically-shaped side walls and end walls fitted within the side walls,

the end walls being dished inwardly, a comparatively non-corrodible sheet metal liner extending over the inner surfaces of the shell, said liner including side portions extending over the side walls of the shell and end portions extending over the end walls of the shell, said side portions being formed of corrugated sheet metal with the corrugations extending longitudinally with respect to the tank, said side and end portions of the liner having cylindrically-shaped overlapping marginsinterposed between the side and end walls of the shell, said margins of said side portions being free of said corrugations, said overlapping margins having their contacting faces bonded together to form a sealed joint and also having their inner and outer peripheral surfaces bonded to adjacent surfaces oi the shell, the end edges of the shell extending beyond the adjacent edges of the end walls and being bent inwardly to form annular recesses adjacent the end edges of the liner, said recesses being filled with hard solder, thereby locking the ends to the side walls of the shell with said solder providing for transmission of endwise thrust on said end walls to said side walls.

ARTHUR J. KERCHER. 

